Sighting device for trench diggers



March 6, 1928. 1,661,812

I v A. A. SMITH SIGHTING DEVICE FOR TRENCH DIGGERS 2 Sheets-Sheet 1 Filed March 3. 1927 March 6; 1928. 1,661,812

A. A. SMITH SIGHTING DEVICE FOR TRENCH DIGGERS Filed March 3, 1927 2 Sheets-Sheet 2 I N VEN TOR.

A TTORNEY5 Patented Mar. 6, 1928.

UNITED STATES irasiz ALBERT A. SMITH, or nnnxnny, MICHIGAN.

SIGHTING nnvronron Tammi Dress Rs.

Application filed March 3', 1927-. Serial at. 172,241.

This invention relates to asighting device for excavating machine, particularly trenching machines which move over the ground and dig a trench or ditch. These machines 5 are ordinarily of considerable length and include a boom equipped with an endless carrier fora multiplicity of diggers, scrapers, shovels or other instrumentalities by which earth is loosened and removed for m the formation of a trench or ditch of desired depth. The boom has one end pivotally mounted on they machine proper and a raising and lowering chain is connected to the boom intermediate its ends. It is the present practice to position a plurality of targets or indicators along a trench or course and sufiiciently in the rear of the machine toassistthe operator of the machine in properly guiding the machine and judging the po si tion of the machine for digging a ditch of desired depth. Very often uneven and irregular ground is encountered with the result that one or the other end of the machine will be above or below the normal level of the ground with the result that the boom is supported whereby .a trench orditch is dughaving an unevenand irregular bottom. In other words, the trench or ditch is not of a uniform depththroughoutrelative to a predetermined grade.

My invention aims to obviate the above defects in trench digging by equipping a trench machine with a sighting device adapted to cooperate with targets in indicating to the operator of thetrench machine when the boom should be raised or lowered, also the degree of adjustment, so that irrespective ofythe uneven or irregular surface on which the machine travels a trench or ditch may 40 be dug having a bottom uniform throughout. v 1

The sighting device is applicable to; any trench machine that has a boom or digging instrumentality adapted to be adjusted, and the device includes a double pendulum action by which. a sight member is automatically adjusted. Comparing this sight with targets it is possible for the operator of the machine to determine the positionof the outer end of a boom relative to a predetermined.

grade and consequently may adjustthe boom when incorrectly supported for: maintaining a uniform trench or ditch bottom.

On account of uneven and irregular to ground one side of the machine-may be lower than, the other portion of the device 3 thus tilting the sight member, whicl'r whencompared to the targets, might mislead the operator, causing the trench to be dug tooshallowor too deep. This would result in an uneven trench bottom and-a few inches difference often interferes with the laying of pipes, particularly at joints. The double pendulum action maintains the sight constantly horizontal, yet permits of it raising and lowering ac-. cording to the action" of the machine.

My invention will be' bette'r understood when reference is had to thedra wingsand the 'detail descriptionthereof, the drawings showing the sighting device in two forms, either of 'which may be used. A

Figure 1 is aside elevationof a'portion of a trenchmachineprovided with the sighting device;

Fig. 2 is a perspectiveview of the device illustrating diagrammatically its position relative to a trench andtargets;

Fig. 3 is .averticalfsectional view ofa Fig. 4 is a horizontal sectional view taken on the line 4'4eofFig. 3;

Fig. 5 is a similar View takenon the line 5-5 of Fig S; and

Big. 6 is a perspective view of a rockable sight member 1 T l In the drawings thereference numeral-1 denotes a cab or somestationai'y member at the rear end of a trench or'ditch digging 'niachine and adjustable relative to this machine member is a movable boom2 adapted to be raised and lowered in a vertical plane, the; boom including a driven carrier or conveyor 3 having a plurality of digging instrumentalities 4. This boom 'may be raised and lowered by a suitable mechanism, generally designated 5, and the digging instrumentalities are adapted to"produce a trench o'r'ditch GL' After a, portion of the trench is dug or "the course of the'trench is laid out two or more'targets'Z are placed in position, these targets being of a predetermined height'and in alin'e'ment so that the operator of the trench machine may be guided by the targets and regulatethe posi- "tion of the boom Q'sothat a trench may be dug thatis of a uniform grade.--

My sighting device is adapted to be supported from the stationary member 1 of the machine and convenient to the operator of the machine, so thatthe sightin device may becoxnp'ared with the targets The device comprises parallel bars 8 having the tends into the slotted crank portion 20 of longitudinally of the machine;

inner ends thereof pivotally connected, as at 9 to the stationary machine member 1. The outer ends of the bars 8 are pivotally connected, as at 10 to an upright 11. The distance between the pivot points on the upright 11 is equal to the distance between the pivot points 9, 9. The. structure may be regarded as a parallelogram having a leg 9, 9 on the fixed part of the machine and it is by virtue of this parallelogram arrangement that the bars 8 will remain constantly in parallelism and constantly support the upright 11 parallel to the stationarymember 1.

Pivotally connected tothe boom 2 is a gauge arm 12 provided with a series of apertures 13 representing graduations in elevation. The upper free cndof the arm 12 is adapted to be pivotally connectediby a pin 14 or other pivotal means to the lowermost arm 8, so that the connection between the arm-and bar may be. easily changed. Obviously any up and down movement of the boom is translated to the adjustable parallelogram structure and the movement of the bar maybe noted relative to the target 7 by comparing the posit-ion of the outer end ofthe parallelogram structure with the targets. In connecting the gaugearm 12 to the lowermost bar 8 of the parallelogram structure, I desiretoresort to a ratio of connection based on its connection with the boom. It is by virtue of the apertures 13 and pin 14 that the gauge arm may be positionedrelativeto the lowermost bar 8 so that the distance between the pin 14 and the pivot 9 is in proportion to the distance between the pivot of the boomand the gauge armconnection with said boom, also the distance betweenthe pin 14 and the outer end of. the bar 8 is in proportion to the distance between the outer endof the boom and the gauge-arm connection therewith. This insures a degree of accuracy that might not.

otherwise bev attained. j

' On the upper end of the'upright 11 is a detachable bracket. 16 fixed to the upright by bolts 16 passed through slots 16 in the bracket, whereby the latter may be adjusted Pivotally mounted in said bracket isthe upper angular end 17 of a. pendulum 18. The bracket 16 is made adjustable for fine adjustments that ordinarily could not be attained by the apertures 13 of the arm 12. The pendulum is adapted to swing in a vertical plane parallel to. the direction of machine travel and adjacent the lower weighted end of said pendulum is a pin 19. This pin exa sighting member 21, which is pivotally connected, as at 22,130 thelower end of the upright-Q11. The sighting member 21 extends longitudinally of the machine and has its front end provided with a sight 23 and its rear end with a counterbalance 24. The

counterbalance 24 is for the sight 23 and the pendulum 18 is adapted to take care of the ups and downs of the front wheels of the machine, which of necessity would cause a variation in the depth of the trench. Under normal operating conditions the sight 23 is in alinement with the targets 7 and in the same horizontal plane as said targets. If uneven ground causes the machine to be raised or lowered obviously the sight member 21 is raised or lowered by the machine and the operator can determine whether the sight 23 is above or below the plane of the target 7. If above the. plane of the targets the boom 2 is lowered until the sight 23 is in the plane of the targets and lowering of the boom would dig the trench' deeper so as to maintain a trench bottom grade parallel to the plane of the targets and the trench of uniform grade. If the sight 23 is lower than the plane of the targets the boom is raised, and by the operator keeping his eye on the sight 23 when uneven and irregular ground is encountered may adjust the boom 2 and thus obtain a uniform bottom for the trench.

A modified form of sight member is shown in Fig. 6 wherein a slotted clip' 25 supports a rockable sight member 26 provided with a'counterbalancc 27 for the sight 28. This rockable sight member operates as a pendulum to compensate for sidewisc tilting of the trench machine. I The slotted clip 25'inay be easily mounted on the upright 11 so that the pendulum 18 can be operatively connected thereto.

1. A sighting device for a trench digging machine, comprising a parallelogram having a fixed leg on i stationary part of the ma chine. a gauge arm connected to said' parallelogram and adapted for support from a movable part of the machine, a pendulum carried by saidstructurc, and a sight mem ber articulated with said pendulum and adapted to be moved thereby.

2. A sighting device as called for in claim 1, including also means for balancin said sight member for a constant horizonta position relative to a grade surface.

3. The combination of a trench digging machine having a movable boom adapted to be raised and lowered. a structure pivotally connected to a fixed partof said machine and to said boom, a sight member pivotally connected to said structure and adapted to he raisedand lowered in synchronism with said boom, and means on said structure affected by movement of said structure and adapted for raising and lowering said sight member relative to said structure.

4. The combination of a trench digging machine having a movable boom, adapted to be raisedand lowered, a structure pivotally connected to a fixed part of said machine and to said boom to move in a vertical plane under the influence of said boom, a slght member pivotally connected to said structure to move in a vertical plane, a pendulumv connected to said structure and engaging said sight member to move it in synchronism With said pendulum, and means maintaining said sight member constantly horizontal.

5. A sighting device for a trench digging machine having an adjustable boom, said device comprising an articulated parallelogram structure, a gauge arm adapted to connect said structure to the machine boom, a pendulum carried by said structure, and a counterbalanced rockable sighting member carried by said structure and adapted to be actuated by said pendulum.

6. A sighting device for a trench digging machine, comprising a parallelogram having a fixed leg on a stationary part of the machine, a gauge arm adjustably connected to said parallelogram and adapted for support from a movable part of the machine, a pendulum carried by said parallelogram, and a sight member articulated with said pendulum and adapted to be moved thereby.

In testimony whereof I aflix my signature.

ALBERT A. SMITH. 

